I'm up in the mountains in California, in Tehachapi. I've stored many of my drums in a shed for a decade (small house), but it is a shed I built, to code. California is dry so even with the snow we (used to) get up here I've had no climate issues. I'm getting ready to build a "studio" (aka shed) as an upgrade where I can also set-up and play. Our property is rural so noise/neighbors aren't that much of a problem but my wife will only let me play e-drums in the house. I will build the studio myself and figure it will costs about $3,000 for the materials, insulated though with windows and (at least some) solar power. If you are handy with construction, this is no big deal. But the major issue is zoning and structure size. I don't want to pay for a building permit which, where I live, means it can't be on a permanent foundation (e.g., bolted to a concrete pad), and is supposed to be no more than 140-sq ft (10x14-ft, pretty damn small. But if it's not permitted it won't be inspected and will anyone measure it?). I'd be very careful about Tuff-sheds and those pre-fab wooden sheds like they sell at Home Depot. The Tuff-sheds are water proof but not much else; the pre-fabs are made with 1x3s and are pretty damn-flimsy. Neither will give you any sound-proofing. As to concrete pads, two things are guaranteed: they won't blow away in the wind, and they will crack if exposed to the weather (unless they are really thick and include a lot of rebar). I'd elevate the shed above the pad using blocks, but the pad is a good way to keep weeds from growing underneath.